(Not Applicable)
(Not Applicable)
The present invention relates to mechanical split seals. Mechanical split seals are employed in a wide variety of equipment, such as pumps, to provide a pressure-tight and fluid-tight seal between one environment having a pressurized process fluid and an external environment containing the equipment. The split seal assembly is usually positioned about a rotating shaft that is mounted in and protruding from a stationary part of the equipment.
Conventional split seal assemblies include face type mechanical seals, which have a pair of seal faces that are concentrically mounted about the shaft. The seal faces have smooth radial primary sealing surfaces that are in contact with each other. Usually one seal face remains stationary while the other seal face rotates with the shaft. The split seal assembly prevents leakage of the pressurized process fluid to the external environment by biasing the seal faces in contact with each other. For example, a split seal assembly may include one or more springs, which urge the seal faces together.
The rotary seal component includes a rotary seal face which is usually mounted in a rotary holder. The rotary holder includes a pair of holder halves, each having a pair of mating surfaces, that are fastened together. A set screw is generally used to secure the rotary seal component to the shaft. The stationary seal face is usually mounted in a piece called a gland. The gland also includes a pair of holder halves, usually referred to as gland halves, each having a pair of mating surfaces that are fastened together. In an assembled split seal, the rotary seal component is disposed within the gland, so that the primary sealing surfaces contact one another.
The mating surfaces of the rotary and stationary holder halves are normally manufactured to tight tolerances. Typically, each holder half has a groove formed on one of the mating surfaces for mounting a sealing gasket. When the gasket is mounted within the groove and the halves are secured together, the gasket contacts the opposite mating surface of the half. This contact forms a pressure-tight and a fluid-tight seal between the halves.
The seal faces are often divided into segments, each segment having two split surfaces. Because the seal faces are split, they can be mounted about the shaft without freeing one end of the shaft. Frequently, the split between the split surfaces is angularly offset from the junction between the mating surfaces. The split seal assembly has a distinct advantage over non-split mechanical seal designs in that the total time to install the seal is reduced because the rotating equipment does not have to be dismantled.
Axial alignment of the primary sealing surfaces and concentricity of the seal faces with the shaft are conducive to forming a good seal. Maintenance of the axial alignment and concentricity retains a good seal under pressure.
Axial alignment may be easily and quickly achieved by seating the seal face of one of the seal components rigidly in the holder halves. By providing circumferential axial support for this seal face, distortion of the primary sealing surfaces even under high pressures may be reduced or eliminated. The holder halves may be configured to form the seal face concentrically with the shaft and to maintain the concentricity under pressure. The face of the other seal component may be resiliently supported.
In one aspect, a seal component has a circular seal face and first and second holder halves. Each seal face includes two seal face segments. Each seal face segment has a primary sealing surface. A section extends axially from each primary sealing surface and a nose extends radially from each section. The nose of each seal face segment is mounted within each holder half. The seal face may be rigidly mounted.
Each holder half may have a recess. The nose of one of the seal face segments may be within the recess. The nose contacts against a lip of the recess when pressure is applied to the seal face in a direction opposing the primary sealing surfaces.
Each holder half may include a channel having an inner axial wall and an outer wall. One of the seal face segments may be within the channel.
Each holder half has first and second mating surfaces. An aligning pin may extend from each of the second mating surfaces. Each of the first mating surfaces may have an aligning hole which snugly receives one of the aligning pins. When the holder halves are positioned such that each of the aligning pins is received within each of the holes, the holder halves are axially and radially aligned with each other, and the aligning pins are retained within the holes upon release of the holder halves.
The seal component may further include a split o-ring between an inner wall of the section extending from the primary sealing surface and a rotating shaft upon which the seal component is mounted. The split o-ring centers the seal face with the shaft. Alternatively, the split o-ring may be in a recess in the inner wall. In another configuration, the inner wall includes an axial wall and a conical wall, the conical wall extending from the axial wall. The split o-ring is against the conical wall.
In another aspect, a seal component has two seal face segments and first and second holder halves. Each seal face segment includes a primary scaling surface and a section extending from each primary sealing surface. Each section has an outer wall. Each holder half includes first and second mating surfaces and an integral band having an inner wall. The inner walls surround the outer walls and secure the seal face segments rigidly and concentrically around a rotating shaft.
Each of the integral bands may be attached to each of the holder halves at each of the first mating surfaces. The inner walls and the outer walls may be, for example, semi-cylindrically shaped or semi-conically shaped. Each integral band may have a first and a second flanged section. The second flanged section may have a lip protruding from an outer edge. The first flanged section may have a complementary notch. The lip of each integral band is in the notch of the other integral band.
In yet another aspect, a seal component comprises a seal face and first and second holder halves. Each half includes first and second mating surfaces and an outer wall. Each of the walls extends from the first mating surface to the second mating surface. The outer walls have a stress-relief proximate the first and second mating surfaces. Each half may further include an inner axial wall that has a stress-relief proximate the first and second mating surfaces.
In a further aspect, a rotary seal component kit comprises two rotary seal face segments and first and second rotary holder halves. Each seal face segment has a radial primary sealing surface, a section extending from the primary sealing surface and a nose extending radially from the section. The nose of each seal face segment is mounted within each holder half. Each holder half may have a recess with the nose of each of the seal face segments within each recess.
Each half may include an integral band which surrounds the section. Each holder half may have first and second mating surfaces, an inner axial wall and an outer wall. The inner axial wall and the outer wall may have stress-reliefs proximate the mating surfaces. A split o-ring may be on an inner wall of the section.
In still another aspect, a seal component includes two holder halves, a split o-ring, and two seal face segments. Each holder half includes an inner axial wall and an outer axial wall coaxial to the inner axial wall. Each outer axial wall has a groove. A split o-ring is in the grooves. Each seal face segment has a ridge. The segments are between the inner and outer axial walls of each half. Each segment is supported by at least one resilient support axially pushing the segment away from the holder half. The inner axial walls maintain the segments concentric with the shaft during assembly and installation and retain the resilient supports. The ridges abut against the split o-rings preventing the seal face segments from axially separating from the holder halves.
A method of assembling a seal component half includes inserting a split surface of a seal face segment into a channel of a holder half, so that a nose extending radially from the seal face segment enters a complementary recess in the holder half, and moving the seal segment along the channel until the seal face segment is fully seated in the holder half. The method may further include adhering a split o-ring to an inner wall of the seal face segment.
A method of assembly and installation of a seal component includes assembling first and second seal component halves and uniting the component halves around a shaft. The first component half includes a first holder half, and the second component half includes a second holder half. Each holder half has a counterbore and a seal face segment. A nose extends from each seal face segment. The nose is retained in the counterbore.
Each holder half may have a first and second mating surface. The second surface may have an aligning pin and the first surface may have an aligning hole. The uniting may further include inserting each of the aligning pins into each of the aligning holes. The method of assembly and installation may further include placing a fixture between each holder half and a radial surface opposing a primary sealing surface of each seal face segment. Insertion of the fixture axially aligns the seal face segments.
Another method of assembly and installation of a seal component includes inserting seal face segments into first and second holder halves. Each seal face segment has an outer peripheral surface. Each holder half has an integral band surrounding one of the outer peripheral surfaces. Next, the holder halves are placed around a shaft. Finally, the integral bands are fastened one to another.
A split seal assembly includes first and second seal components. The first seal component has a circular seal face with two seal face segments. Each seal face segment has a nose. The first seal component also has two holder halves. The nose of each seal face segment is mounted within each holder half. The second seal component includes a resiliently mounted seal face.